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排序方式: 共有199条查询结果,搜索用时 15 毫秒
1.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
2.
Todd Rowland 《Complexity》2006,12(2):13-29
We present a network experiment that investigates the computational power of cellular automata on the simplest irregular lattice. One cellular automaton whose apparent complexity increased is Rule 60, the left neighbor Xor operator. It went from being nested to complex. That makes Xor a candidate for universal computational power. We present the evidence in terms of the size of cycle lengths, transients, and size of boolean expressions. © 2006 Wiley Periodicals, Inc. Complexity 12: 13–29, 2006 相似文献
3.
D. R. Rowland 《Optical and Quantum Electronics》1990,22(4):369-373
A geometrical method for determining the power transfer between piecewise uniform, alternating , twin-core linear directional couplers is presented. Phase space provides the basis for the method. 相似文献
4.
M.P. Irion W.D. Bowers R.L. Hunter F.S. Rowland R.T. McIver 《Chemical physics letters》1982,93(4):375-379
Ions produced by multiphoton ionization (MPI) of naphthalene, fluoranthene and triphenylene have been detected by Fourier-transform mass spectrometry (FT MS). Paret ions are produced very efficiently at 250 and 222 nm with pulse energies as low as 1 mJ. With FT MS a complete, high-resolution mass spectrum is obtained for each laser pulse. 相似文献
5.
The problem of defining N(E), the density of states, for molecular systems is discussed. It is shown that a numeric evaluation of N(E) is often only approximate, even for continuous data, and is not well defined for quantized systems. The application of the concept of density of states is discussed, particularly with regard to the RRKM theory of unimolecular reactions. The sum of states, W(E), and density of states curves are evaluated for several harmonic and anharmonic model systems and the results discussed in order to illustrate the foregoing considerations. 相似文献
6.
Alberti G Brunet E Dionigi C Juanes O de La Mata MJ Rodríguez-Ubis JC Vivani R 《Angewandte Chemie (International ed. in English)》1999,38(22):3351-3353
The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space. 相似文献
7.
8.
9.
S. P. Rowland V. O. Cirino A. L. Bullock 《Journal of polymer science. Part A, Polymer chemistry》1971,9(6):1677-1683
Cotton cellulose in fabric form was crosslinked with divinyl sulfone by catalysis with solutions of sodium hydroxide of normalities ranging from 0.1 to 4.0. The molecular chains of cellulose were hydrolyzed with sulfuric acid to yield hydrolyzates from which simple substituted glucoses (i.e., those bonded to a single unit of DVS), the simple crosslinked glucoses (i.e., those joined together by a single unit of DVS), and complex structures (i.e., those substituted or crosslinked with more than one unit of DVS in the chain) were isolated and measured. The fractions of the reagent residues in the forms of the structures noted above were found to change substantially with the concentration of base employed to catalyze the reaction. The constitution of the reagent residues resulting from reaction in 0.1N base was remarkably simple: 82% of the DVS residues in the form of simple crosslinks and 18% in the form of simple substituents. Complex structures accounted for as much as 70% of the DVS residues under other conditions of reaction. 相似文献
10.
Reaction of Cu(ClO(4))(2) x 6H(2)O with a racemic mixture of the novel chiral ligand N-(1,2-bis(2-pyridyl)ethyl)pyridine-2-carboxamide (PEAH) affords only the homochiral dimeric copper(II) complexes [Cu(2)((R)()PEA)(2)](ClO(4))(2) and [Cu(2)((S)()PEA)(2)](ClO(4))(2) in a 1:1 ratio. The phenomenon of molecular self-recognition is also observed when a racemic mixture of the monomeric copper(II) complex [Cu((R(S))()PEA)(Cl)(H(2)O)] is converted into the homochiral dimeric species [Cu(2)((R(S))()PEA)(2)](ClO(4))(2) via reaction with Ag(+) ion. This is the first report of direct conversion of a racemic mixture of a chiral monomeric copper(II) complex to a mixture of the homochiral dimers. 相似文献